1. Field of the Invention.
The present invention relates to an electrically powered radiant heater for analytical laboratory use and, more particularly, to a radiant heater for analytical laboratory use having a controller for receiving input power from the power source and processing output power to the heating means to deliver heat to a sample being heated at a programmed rate until a preselected temperature is reached for a preselected time interval all within a programmed schedule.
2. Description of the Prior Art.
There is a constant need for clean radiant heat in both research and development facilities, as well as in process applications in the medical, pharmaceutical, electronic, and semi-conductor, defense/aerospace, food processing, painting, coating, restaurant, automotive and petroleum fields. For example, automobile glass companies that produce nonfogging glass have manufacturing areas with a clean environment. The processes involved in the production of medicine and the like which require drying the final product during the production process require clean heat. The electronic industry needs a clean heat environment for the production of semi-conductors for the computer industry. The application of polymer coatings to circuit boards requires a total absence of contaminating dust or metal. In the coating industry, coatings such as Teflon.RTM. and ceramic are applied to product services in clean environments and often dried for long periods of time during which a clean source of heat is desirable.
At the present, most frequently used radiant laboratory heaters are infrared heating lamps of either 250 watts or 375 watts. The 375 watt infrared lamp achieves a temperature of approximately 105.degree. Centigrade with a sample positioned about two inches from the lamp. The temperature is about 222.degree. Centigrade at the lamp's surface which is not a usable location.
Current infrared heating systems constructed of exposed metal parts can produce a source of contamination to laboratory samples. Contamination is extremely damaging in the analytical laboratory involved in providing accurate trace element determinations. The metal socket receptacle on all infrared heating lamps will eventually corrode when exposed to acid vapors. Since the infrared lamp is not sealed inside a protective housing, the corroded metallic parts from the lamp socket fall in a random manner directly into the analytical sample positioned below which is later subjected to analysis to determine the trace elements present. Thus, the metallic socket particles become combined with the trace elements from the sample contents to yield inaccurate information.
Heat controls on infrared heating lamps range from a plug (full heat) to a variable adjustment knob. These systems are difficult, if not impossible, to use efficiently to provide consistent and reproducible levels of heat such as required in a laboratory environment. Heating conditions that cannot be consistently and reliably reproduced restrict or impede the analyst in the development of precise methodology for sample preparation.
Thus, there is a need for a general purpose laboratory radiant heater having higher heating potential, precise and reproducible heating parameter settings, and greater functional integrity so as not to contaminate samples being treated. It is to this need that the present invention is directed.